Fig. 3. Feedback loop in beach visitors.
Even if water quality improved and the recreational appeal of the beach greatly increased, this would not necessarily result in a greater number of beach users because the beach would already be close to its recreational carrying capacity, especially during the summer months. (Recreational carrying capacity is defined as the number of beach visitors that are physically able to occupy the beach, limited by behavioral norms such as the distance at which the visitors are prepared to sit from each other [De Ruyck et al. 1997]). Conversely, if the recreational appeal decreased due to adverse water quality conditions, the number of visitors would not necessarily decrease significantly. People prefer less crowded beaches; therefore, as the number of visitors decreases due to poor water quality conditions, other people would likely visit because the beach would become less crowded. There is a possible feedback from water quality of the beaches to increased visitors to the local bars and restaurants (indicated by a dotted line), but we did not include this in our model due to a lack of available data.